This invention relates generally to aircraft or small boat dipped sonar systems and particularly to a single conductor charging circuit and data transmission system which can be effectively employed between an aircraft or small boat and a submersible sonar sensor unit. In operating an aircraft dipped sonar system, it is desirable that performance capabilities of the system be maximized as much as possible with regard to the time period over which the aircraft may hover, the length of cable and consequential depth of sensor operation that can be achieved, the speed with which cable payout and takeup can be accomplished and the number of cables required to pass information between the aircraft and the submersible unit. Prior art dipped sonar systems have utilized multiconductor analog signal processing systems as well as the transmission of a high level transmit pulse down the supporting cable thereby requiring relatively heavy insulation and conductors along the cable length. Moreover, both the cable weight and time required for cable takeup and payout increase proportionally with cable bulk thereby creating an increase in hover periods and a consequential reduction in sensor operating time of the system.